AccompanyingPeriod list: adding new wrapheader asset and improve wraplist structure

wrapheader manage header of flex-table first row. the 2 cascades are independant.

src/Bundle/ChillMainBundle/Resources/public/chill/scss/flex_table.scss

@@ -203,3 +203,36 @@ div.wraplist {
         }
     }
 }
+
+
+/*
+*  __WRAP_HEADER_BLOC________
+*  HEADER ROW FOR FLEX-TABLE ELEMENTS
+*/
+
+div.wrapheader {
+    width: 100%;
+
+    div.wh-row {
+        display: flex;
+        flex-direction: row;
+
+        &:first-child {
+            align-items: baseline;
+        }
+        &:last-child {}
+
+        div.wh-col {
+            &:first-child {
+                flex-grow: 0; flex-shrink: 1; flex-basis: auto;
+            }
+            &:last-child {
+                flex-grow: 1; flex-shrink: 1; flex-basis: auto;
+
+                display: flex;
+                justify-content: flex-end;
+            }
+        }
+
+    }
+}